Telephone-exchange system



March 16 1926.

A. B. SPERRY TELEPHONE EXCHANGE. SYSTEM Filed Nov. 6,

Patented Mar. 16, 1926. i i i UllllTiE is T E- earner trier.

ARTHURB.ernhngordmr roian, n. Y i, rissionon re wesessnseeeearc COM- PANY, INCORPORATED, ornnw'roan, n. a-eeneeearionos new YORK.

TELEPHONE-EXCHANGESYSTEM. v v

Application 'filetl Novcinber 6, 1924; Serial 3T0. 748,050.

To all whom itmag concern: I, i the removalof the receiver thereat to cause Be it known that I, ARTHUR B. SPERRY, a the lightingo'f a line lainp hefore the operator citizen of the United States, residing at in the usual manner. In response to the New York city, in the countyfof New York lighting of the lamp, not shown, the opand State of New York, haveinvented ce1' orator inserts the answering end oi one of tainnew and useful Improvements in Telethe position cord sets into the jack assophone-Exchange Systemaof which the fol ciated with the lighted lamp and depresses lowing is a fulhc'le'erncencise, and exact dethelistening key lOassociated with the se scription. v lected cord circuit to connect her head set to This invention relates .to telephone exthe calling substation. After receiving the changcsystemsandmoreespccially it has to number of the desiredparty, assuming that do with telephone s' stems of the class the called partys line is located in a distant wherein automatic switching apparatus is office and is available only through a'tandem employed in a main exchange for the estabotlice,'the operator withfthe calling end of lishment of conversational connections bethe selected cord circuit tests in the usual tween two other main exchanges; v way for busy trunks leading to the tandem Forthe sake of clearness the two latter point and then plugs into the jacl; that is exchanges will be referred to hereinafter as connected-tothe first idle trunln lVhen the the originating and terminating otiices, recalling plug is fully inserted in the trunk spectively, while the intermediateexchange jack a circuit is closed from ground, 7 will be known as thetandemofilce. In this through the windings of sleeve relay 107 disclosure oi the invention the apparatus and relay 106, lamp 105 to battery. Relays employed in the originating office is of the 106 and 107 operate, relay 107 closing an semi-automatic switching type and-that used obvious circuit to operate relay 108. The in the terminating othce is of the manually operation of relay .108 closes at its inner 5O operated'type. Inthis systemthe means in right armature an operating circuit for rethe tandem office for establishing a conneclay 109 'the circuitheing traceable from hattion comprise step-by-step selector or trunlztery, through the lower right winding of huntingswitches. repeating coil 118, through thewinding of The object of the invention is an imrelay 103, ring side of the cord and trunk proved method for preventing trunk-huntcircuits, conductor 1-21, normal contact of iug over a selector switchvhank should all relay 109 and through winding thereof to the trunks in the desired group beshusy and ground atfthe inner right armature of relay for permitting the hunting when a'trunl: in 108. Relay 109 operates and locks at its that group becomes idle. inner left contact in a circuit ext nding to 9 A feature or" the inventionresides in the battery at the outer left armature of relay manner in which the operator is kept in- 108. The relay '109 connects at its outer lel't formed of the progress of the connection. armature, the winding of relay 110 to the Other features and. advantages will he ring sideot the trunk circuit, and closesat apparent after a consideration of the folits inner right 'armaturean obvious operatlowing detailed. description and the aping circuit tor the pulsing relay 113. The pended claims. operation of, relay 113 connects the bridge The drawings consisting of two figures of the polarized relay 11% across the conillustrate a complete trunk connection he ducting end of the trunlrcircu'it, thereby tween two oiiices, the connecting means hepreparing the selected trunk circuit to the .ing located in 7 an intermediate or tandem tandem otfice for dialing.

ofli'ce. Fig. 1 shows a calling substation, an The operator now depresses her dialing operators dialing; cord'j circuit, and a trunk; ke'y 1-15 and operates the position dial 116 outgoing from the originating office, and to connect the selected idle trunlz'toanother Fig. 2 sho vs trunks incoming and outgoing idle trunk outgoing from the tandem office from the tandem ottice together with'the asto the particular otiice in which the called sociated autoniaticswitching apparatus and subscrih'ers line terminates. When the dial also the extension of the trunk to the ter-' moves ofi' normal position, the circuit preminating' ofiice. viouslyifirepared at the outer left armature The'caliin' substation 100 is adaptedupon of relay 109 is closed at thc'left spring and inner contact ot the dial to operate the relay 110, the circuit being traceable from battery at outer left armature of relay 108, through the winding of relay 110, contact and armature of relay 117, outer left armature and contactof: relay 109, conductor 121, ring side 01' trunl; and cord circuits, lower ell-normal contacts of key 115 to ground at inner left contact of the dial. During the time that the dial is in oll'-nor1nal position, this ground connection remains steady to hold the relay 110 operated during the sending of the pulses. The operation of relay 110 opens at its make-beforebreak contact the operating circuit for pulsing relay 113 but closes simultaneously at its inner right armature and front contact another operating circuitextending to ground at the righthand spring of the dial 116. This substitute ground holds the relay 113 operated until the operator releases and permits the dial to return to normal, which return movement causes interruptions in this sub stitute ground connection corresponding in number to the digit dialed.

For each pulse received by relay 113, a circuit is closed extending from battery, through the rightdiand winding of relay 20S, outer normal contact of relay 20+ outer left ari'nature and back contact of relay 2-08, ring side of trunk, through the winding of polarized relay 11-11, contact and armature of relay 113, tip side of trunk, inner left armature and back contact of relay 208, iiiner normal contact of relay i Ol, through the left-hand winding of relay 203 to ground. A direct bridge across the tip and ring of the trunk is also closed through the inner left front contact of relay 110. Pulsing relay 203 operates in this circuit but relay 111 due to its polarity is not aill'ected. The first pulse operating relay 203 causes the operation of relay 205 which, being of the slow-to-release type, is maintained in an operated condition during the subsequent pulses of the digit dialed. At the end of the first pulse relay 203 deenergizes and closes at its back contact an operating circuiti for the primary stepping magnet 206 of the selector switch which is associated with the particular trunk selected, the circuit being traceable from battery, through the winding of magnet 906. left-hand low resistance winding of relay 207. left front contact of relay 205, back contact 03f relay 203 to ground at the inner right armature of relay .208. Relay 207 is made slow-torelease so as to be non-responsive to the subsequent pulses of the dialed digit. The relay 207 and the magnet 206 operate, and the operation of the niagnet starts the primary movement of the selector switch brushes 5209, 216, 217 and 218 upwardly over their respective terminal banks, the brush .209 being associated with the commutator bank, each level of which corresponds to a group of outgoing trunks leading to a tern'iinating ollice. For each succeeding pulse the brush 209 is stepped upwardly one level until the desired group is reached.

When the brushes start their primary movement the lower contacts of oil-normal springs 21% close an operating circuit for relay 215, the circuit being traceable from battery, through the winding of relay 215, lower contacts of oil-normal springs 21 1, right armature and front contact of relay 207 to ground at the right armature of relay Relay 215 operates and prepares at its right armature an operating circuit for the secondary stepping magnet 213, but due to the operated condition 0t relay 207, magnet 213 is prevented from operating.

Assuming that No. l on the dial corresponds to the group of trunks extending to the ellice in. which the called subscribcrs line terminates, one pulse will be t 'ansn'iitted by the dial and the brush 209 will step up to the first lOYQl and stop on terminal 210 which corresponds to the group of trunks extending to the desired otlice. After the pulse has been received by relay 203 and the relay has energized and subsequently deenergized, transmitting thereby a pulse to operate the magnet 206, the slow-to-relcase relay 207 deencrgizes but only after a time sutlicient to allow the oll'-normal contact springs 214 to close their contacts. The closing of these contact springs establishes a holding circuit for relay 215, the circuit being traceable from battery, through the winding of relay E215, lower contacts 01 oft-normal springs 21%., armature and contact of magnet 213, left armature and contact of relay 215 to ground at inner right armature of relay 208.

It all the trunks in the desired group are busy, each of the respectively associated re lays a, a and a of the chain relay group will be in an operated condition and the terminal 210 will be coi'ineeted to ground at the right armature of relay a lVith the brush 209 in contact with terminal 210 this ground connection completes a circuit extending through the right-hand high resistance winding of relay 20?, to battery. '1 his circuit holds the relay 20'1" in an operated condition so as to prevent the energization of secondary stc uping magnet 213, thereby holding the switch at a standstill until an idle trunk in the desired group is available.

In the nieantinie, the dial has returned to normal and the ground connection at the inner contact of the left-hand spring of the dial has opened, thereby decnergizing relay 110. Relay 110 opened at its inner right armature and trout contact the pulsing circuit: it"or relay 113, but the latter relay is inunediately rcenergizced by the closing of the lllilliQdX?fOIC- lll'GdlC contact of relay 110. The reencrgization of relay 113 closes a winding of relay 204, lett front contact of relay 207, front contact of relay 203 to ground at the inner right armature of relay 208. Relay 204 is made slow-acting in order to prevent its operation when relay 203 was previously ope ated by the pulsing current. The operation of relay 203 also closes a parallel circuit to operate the relay 205, the

1 operation of which closes aholding circuit for 'relay1215. The interrupter 232 effects pulsations in the operating circuit for relay 20s in comparatively rapid succession, although considerably slower than the pulses which are transmitted by thedial, and these pulsations cause corresponding reversals of battery and ground in the circuit through the winding of polarized relay 114. Relay 114 now responds tothe repeated energiza tions of relay 20% and accordingly closes at its armature an intermittent operating circuit for supervisory relay 120, the circuit being traceable from battery, through the winding of relay 1120,110111121 contact of the left-hand spring of dial 116, lower ollnormal contact of key 115, ring side of cord and trunk circuits, conductor 121, front contact of relay 114:, outer right back contact of relay 110, through the winding of relay 11.7, tip side of trunk and cord circuits, inner contact of relay 106, upper off-normal contact of key 115 to ground at the right spring of dial 116. Relays 117 and 120 energize and deeiiergize intermittently to correspond with the similar interruptions [effective in relay 11-1, and'the lamp 110 responds to these interruptions .by flashing thereby indicating to the operator that all trunks in the desired group are busy;

lVhen an idle trunk inthe desired group becomes available, its associated relay ot' the relay chain group a, a and a is deener'gized and opens theholding circuit for relay 207. The deenergization of relay 207 closes at its make-before-brcak contact the operating circuit for secondary stepping magnet 213, which circuit is traceable from battery, through thewinding of magnet 213, right front contact of relay 215, make-before- -break contact of relay 207 to ground at the right armature of relay 205. When the right front contact of relay 20'? is opened, relay 215 is maintained operated in a circuit traceable from battery, through the winding of relay 215, lower contacts of oft-normal springs 21 1, armature of magnet 213, left armature and contact of relay 215 to ground at the inner right armature of relay 208-. lVhen inagnet2l3 operates, it opens at-its armature and contact'the holding circuit for relay 215 and the relay deenergizes, thereby opening the operating circuit for magnet The deenergization of magnet 218 213. causes the brushes 209, 21-6, 217 and 218 to rotate over the terminals of the level in which the available trunk is located. The busy condition of the terminals with which brush'216 is associated will close an operating circuit for relay 215 traceable from battery, through the winding of relay 215, lower contacts of springs 21-1, contact of magnet 213, outer right back contactot irelay 208, conductor 230, brush 216 andits associated terminal to ground at .the left armature of the busy trunk relay of the chain relay group. The energization of relay 215 again closes the operating circuit for magnet 218, causing the brushes to rotate another step. This operation will be repeated until the available trunk is reached and relay 215 will not operate inasmuch as the trunk relay, such as (4 is in an unoperated condition, thereby preventing further operation of the stepping magnet 213. The seizure of the idle trunk removes the shunt around relay 208 and this relay having a high resistance winding will operate in a circuit traceable from battery, through the winding of relay 215, lower contacts of springs 214, contact or" inagnet213, through the winding of relay 208, contacts of spring 202, conductor 212 to ground at the right armature of relay 205.- Relay 215 does not operate in this circuit and the operation of relay 20S connects'at its left arinatures the conductors 01" the incoming trunk with the conductorsot the idle out 'oing trunk. Also the operation of relay 208 opens the operating circuit for relays 20st and 114. This causes the deenergization of supervisory relay 120 thereby opening the operating circuit for lamp 119. The lamp is extinguished to indicate to the operator that an idle trunk in theidesired group is seized.

Assuming that terminals 219, 220 and 221 are associated withthe idle trunk, an operating circuit is closed for relay222, the circuit being traceable from battery, through the right-hand winding of relay 222, right-hand normal contact of relay 225, lower left-hand winding of repeating coil 229, terminal 220,

brush 217, ring side of trunk, outer left front contact of relay 208, ring side of trunk extending to the originating oirice, through the winding of relay 1.1a, contact ot' relay 113 to tip side of trunk, inner left front contact of relay 208, tip side of trunk in tandem ollice, brush 21S, terminal 221, upper lefthand winding'ot i'epeating coil 229, lett hand normal contact of relay 225, through the left-hand winding of relay 222 to ground. Relay operates and-closes at its left armature, an ope ating circuit for trunk relay a o'l' the chain relay group. The op eration oi relay (1 closes a holding circuit for relay 208, said circuit being traceable from ground at the left arn'laturc ol. relay (1 terminal 21.0, brush 210, conductor 230, outer right i'ront contact of relay 20$, contacts oi spring 2012, through the winding 01 relay 08, contact at magnet 2.13, lower contacts o1 springs fill, through the winding of relay 21a to battery. This holding circuit at the le ii armatures of relay 20S maintains the connection between the incoming and outgoing trunks in the tandem otlice. Also the operation oi relay of closes at its right armature a contact which builds up a closed circuit, when all the trunks of the group are busy.

The operation of relay closes at its rightarmature an obvious operating circuit for high resistance relay 223. Relay i523 operates and causes lamp 220 to light indicating to the operator at the terminating ollice that a connection is desired with a subscribers line terminating in her oilicc, but relay 321 which is in the operating circuit for relay does not operate at this time inasmuch as it is marginal. The operator in the terminating oilice inserts the answering end of one of her position cord circuits into the trunk jaclr associated with lamp E20 thereby causing the operation of relay .lelay operates and opens the operating c rcuit for relay 223 and lamp 220, and therefore relay L23 dcenergizes and the lamp 220 extinguishes, the supervision at the terminating oll'ice now being had at lamp The insertion oil? the answering end ol' the selected cord circuit closes an obvious operating circuit for marginal relay 221 which now operates and closes at its contact an operating circuit for relay E1155. Relay 925 operates and causes a. reversal in the current llow through the polarized relay 114: and relay 'll l consequently oymralcs.

(hen the [lashing oil lamp 119 ceases, as hereinbeliore described, indicating that an idle trunk is seized, the operator in the original oilice restores her dialing key 115 to normal and when relay 11% operates in the circuit in which the reversal oi current is ellectcd, the reversed current now being steady, closes an operating circuit for supcrvisory relay 103. the circuit being trace able from battery, through the lower right hand winding oi repeating coil 118, through the winding of relay 1023, ring side of cord and trunk circuits, conductor 121, front contact of relay 11-1, outer right back Contact of relay 110, through the winding of relay fl 1i", tip side 01 trunk and cord circuits, through the upper right hand winding of coil 118 to ground. Relay 108 operates and shunts lamp 105 which is extinguished and remains thus for the duration oi. conversation.

Upon the cessation of the conversation the operator in the terminating ollice disconnects the cord circuitt'rom the trunk and relay 2i)? deenergizes causing thereby the closing of the operating circuit for relay L23. Relay 2'23 recnergizes thereby causing the release of marginal relay and the subsequent release of relay 225. The release of relay 225 changes the current flow from battery and ground at relay 222, through the winding of polarized relay 1M to its original direction and relay 11 deenergizes. The deencrgization of relay 11-1 opens the operating circuit for supervisory relay 103 and relay 103 deenergizes thereby removing the shunt around lamp 105 which now lights indicating to the operator at the original ollice that the cord circuit at the terminating ollice has been disconnected. The orig inating operator will now disconnect her cord circuit from the calling subscribers line and outgoing trunk circuit and the equipment in her otlice and the tandem oiliice will restore to normal. The above operations are effective only, if it is assumed that the calling subscriber is still holding his line, but should the calling subscriber disconnect at the same time as the called subscriber, the remaining operated equipment, not restored in the above description, will restore to normal simultaneously with the equipment at the terminating oliice. The removal of the connections in the originating oilice opens the operating circuit for relay 107 which deenergizes and Causes the subsequent release of relays 108, 109 and 113. The release of the armature of relay 11? opens the operating circuit for relay 222, thereby causing the subsequent release of relay a and The deenergization of relay a opens the operating circuit for relay 208, thereby opening the connection be tween the incoming trunk and the associated selector switch brushes, and closing at the inner right back contact of relay 208 an operating circuit for the release magnet 2531, the circuit being traceable from battery through the winding of relay 231, upper contact and spring 5314, left back contact of relay 20:"), right back contact of relay 203 to ground at the right armature of relay 908. The operation of magnet 231 releases the switch brushes and permits them to return to normal. The release magnet Q31 decnergizes when the oil-normal springs 21% are restored with the switch brushes.

llhat claimed is:

1. In a telephone system, a selector switch, a plurality of trunk lines arranged in groups extending from said switch, an operatmds position, a sender at said position arranged to send impulses to select a trunk line in a particular group 01 said switch, a signal at said position, means for preventing the selection of a trunk line and for flashmg said signal should all trunk lines in the desired group be busy, and means effective when.

a particular group-extending to a third of said offices, a signal at said position, automatic means in the second mentioned office for preventing the selection of said trunk line and fol-flashing said signal should all trunk lines in the desired group be busy, and means effective when one of said trunks becomes idle to cause said trunks to be tested.

3. In a telephone exchange system, a plurality of central 'ofiices comprising a semiautomatic, an automatic, and a manually operated office, a plurality of trunk lines arranged in groups extending between said offices, an operators position in said semiautomatic office, a sender at said position arranged to send impulses over one of said trunk lines to said automatic oiiice,a signal at said position, a selector switch in said automatic ofiice comprising trunk terminals arranged in groups, one of said groups being extended to said manually operated ofiice, means associated with said selector switch for selecting a desired group of said terminals, for flashing said signal and for preventing further operation of said means should all said trunk lines in the desired group be busy and for permitting further operation of said means when a trunk line in the desired group is available to complete a trunk line connection to the said manually operated ofiice, and means effective when One of said trunks becomes available to cause said trunks to be tested.

4. In a telephone exchange system, a plurality of central offices comprising a semiautomatic, an automatic, and a manually operated office, a plurality of trunk lines extending between said ofiices, an operators position in said semiautomatic ofiice, asender at said position arranged to send impulses over one of said trunk lines to said automatic office, a signal at said position, a selector switch in said automatic office comprising trunk terminals arranged in groups, one of said groups being extended to said manually operated ofiice, automatic means associated with said selector switch for selecting a desired group of said terminals, for preventing further operation of said automatic means and for flashing said signal should all trunk lines in the desired group be busy and for permitting further operation of said automatic means when a trunk line in the desired group is available to complete a trunk line connection to the said manually operated oflice, and means efi'ective when one of said trunks becomes avail- ARTHUR B. SPERR-Y. 

